SmogRank / Thailand / Chai Nat / Chai Nat
Chai Nat, month by month
Chai Nat has a measured daily mean on 608 days since 5 April 2023. Its worst month was April 2026, at 141 US AQI (51.6 µg/m³), 66th of 2,941 cities on that month's world ranking. Its cleanest was September 2025, at 49 US AQI (8.8 µg/m³).
Every month since 2023
The US EPA's Air Quality Index for PM2.5 (2024 breakpoints). Show values as: µg/m³ · US AQI · India AQI · China AQI · European AQI · UK DAQI · Canada AQHI+. About the scales
Months without a mean, and why
24 months
| Month | Why |
|---|---|
| Jul 2026 | 3 of 31 days measured; a month needs 22. The others: 28 with under 18 hours of readings or readings that failed our checks. |
| Nov 2025 | 12 of 30 days measured; a month needs 21. The others: 18 with under 18 hours of readings or readings that failed our checks. |
| Oct 2025 | 10 of 31 days measured; a month needs 22. The others: 21 with under 18 hours of readings or readings that failed our checks. |
| Aug 2025 | 6 of 31 days measured; a month needs 22. The others: 25 with under 18 hours of readings or readings that failed our checks. |
| Jul 2025 | No day measured. The others: 31 with under 18 hours of readings or readings that failed our checks. |
| Jun 2025 | No day measured. The others: 30 with under 18 hours of readings or readings that failed our checks. |
| Jan 2025 | 5 of 31 days measured; a month needs 22. The others: 26 with under 18 hours of readings or readings that failed our checks. |
| Dec 2024 | 1 of 31 days measured; a month needs 22. The others: 30 with under 18 hours of readings or readings that failed our checks. |
| Nov 2024 | 3 of 30 days measured; a month needs 21. The others: 27 with under 18 hours of readings or readings that failed our checks. |
| Oct 2024 | No day measured. The others: 31 with under 18 hours of readings or readings that failed our checks. |
| Sep 2024 | No day measured. The others: 30 with under 18 hours of readings or readings that failed our checks. |
| Aug 2024 | No day measured. The others: 31 with under 18 hours of readings or readings that failed our checks. |
| Jul 2024 | No day measured. The others: 31 with under 18 hours of readings or readings that failed our checks. |
| Jun 2024 | No day measured. The others: 30 with under 18 hours of readings or readings that failed our checks. |
| Mar 2024 | 20 of 31 days measured; a month needs 22. The others: 11 with under 18 hours of readings or readings that failed our checks. |
| Dec 2023 | No day measured. The others: 31 with under 18 hours of readings or readings that failed our checks. |
| Nov 2023 | No day measured. The others: 30 with under 18 hours of readings or readings that failed our checks. |
| Oct 2023 | No day measured. The others: 31 with under 18 hours of readings or readings that failed our checks. |
| Sep 2023 | No day measured. The others: 30 with under 18 hours of readings or readings that failed our checks. |
| Aug 2023 | No day measured. The others: 31 with under 18 hours of readings or readings that failed our checks. |
| Jul 2023 | No day measured. The others: 1 missing from OpenAQ's archive, 30 with under 18 hours of readings or readings that failed our checks. |
| Jun 2023 | 6 of 30 days measured; a month needs 21. The others: 24 with under 18 hours of readings or readings that failed our checks. |
| May 2023 | 15 of 31 days measured; a month needs 22. The others: 16 with under 18 hours of readings or readings that failed our checks. |
| Apr 2023 | 13 of 30 days measured; a month needs 21. The others: 2 missing from OpenAQ's archive, 11 with under 18 hours of readings or readings that failed our checks. |
A day counts once 18 hours of it are measured; a month needs 70% of its days.
Chai Nat's worst months
| Month | US AQI | World rank | Episode |
|---|---|---|---|
| April 2026 | 14151.6 µg/m³ | 66thof 2,941 | – |
| January 2024 | 12244.2 µg/m³ | 48thof 2,385 | – |
| April 2024 | 12143.6 µg/m³ | 42ndof 2,520 | – |
| February 2024 | 12043.1 µg/m³ | 51stof 2,486 | Thailand, February 2024 |
| March 2025 | 11440.8 µg/m³ | 147thof 2,862 | – |
| January 2026 | 10938.8 µg/m³ | 94thof 2,617 | – |
Monthly means over the days measured; finished months only. World rank: its place on that month's world ranking of every city with enough days. Each month opens that ranking.
Chai Nat's worst days
| Day | US AQI | Episode |
|---|---|---|
| 24 Jan 2025 | 18299.8 µg/m³ | Northern Thailand, January 2025 |
| 25 Jan 2025 | 18097.4 µg/m³ | Northern Thailand, January 2025 |
| 17 Apr 2023 | 17690.9 µg/m³ | Thailand, April 2023 |
| 16 Apr 2023 | 17183.4 µg/m³ | Thailand, April 2023 |
| 24 Mar 2025 | 17082.1 µg/m³ | – |
| 25 Mar 2025 | 16778.0 µg/m³ | – |
| 3 Apr 2025 | 16777.8 µg/m³ | – |
| 4 Apr 2025 | 16473.8 µg/m³ | – |
| 16 Feb 2024 | 16473.4 µg/m³ | Thailand, February 2024 |
| 8 Apr 2026 | 16373.0 µg/m³ | – |
Daily means, the highest since 5 Apr 2023; the WHO's daily guideline is 15 µg/m³. Each date opens that day's world ranking, and each episode the bad-air spell it was part of.
Use this history
SmogRank, PM2.5 monthly and daily means, Chai Nat, Thailand, 5 Apr 2023 – 12 Oct 2026. Monitor data from Air4Thai via OpenAQ; sources listed at smogrank.com/sources. smogrank.com/th/chai-nat/history (accessed 12 Oct 2026).
You're welcome to reuse a single chart, image or figure with this citation and a link. Terms. Raw monitor readings in bulk are published by OpenAQ, under each provider's licence.
Chai Nat now: the last 24 hours, its ranks today and the last 12 months day by day.
Updated 2026-10-12 23:07 UTC. Values are PM2.5 (fine particles), the median of each city's monitors, as the US AQI PM2.5 sub-index. Some low-cost readings: Sensor.Community, ODbL (data and licence). Some readings: Uzhydromet (Uzbekistan's Hydrometeorological Service); Department of Environment, Nepal; Vietnam's government monitors; Aurassure; Umhverfisstofnun (Environment Agency of Iceland); RMCAB (Secretaría Distrital de Ambiente, Bogotá); Love My Air (City and County of Denver), no reuse terms published (why we use them).